Washington (CNN) -- Twelve new stars have been recently added to the CIA's Memorial Wall, which pays tribute to the 102 men and woman who lost their lives in the line of duty for the spy agency.

At a ceremony Monday before the wall in the atrium of CIA headquarters, Director Leon Panetta paid tribute to the fallen officers.

"No matter when or where they served, or whether their names are known to the world or only to us, each cherished colleague remains a constant source of inspiration and courage," Panetta said.

Seven of the new stars represent the men and women who were killed last December at a CIA post in Khost, Afghanistan, when a believed-to-be informant they were scheduled to meet detonated a suicide vest. None of the clandestine officers are identified by name.

The other five stars honor officers who died in recent years while on secret missions. Their names and the details of their work remain classified.

"They are our heroes," said Panetta. "They are America's heroes and that's how we will remember them."

Hundreds of current and former employees, family members and friends attended the memorial service.